Condensate unloader valve



July 8, 1952 R. A. BARRETT CONDENSATE UNLOADER VALVE Filed Dec. 12, 1950 2 SHEETS-SHEET 1 a mill/1111119,

IN V EN TOR. Pal 07 ABarriZ BY fliiarney Patented July 8, 1952 UNITED STATES PATENT OFFICE.

CONDENSATE UNLOAD-E-It VALVE Ralph A. Barrett, Cleveland,- Ohio Application December 12, 1950, Serial N0.'20'0,471

This invention relatesto moisture orliquid unloading valves adapted-to be associated: with a conduit system -for transmitting air or 'the'like under pressure in response-to intermittent demands, and more particularly to a valve ofthis type adapted toautomatically; discharge liquid frm;the conduit system'at 'the'initiation and termination oisaid demands.

The valve to be described is particularly adapted toremove water and/or oil=from an air compressor conduit'system or 'from a 'conduit transmitting compressed air to a work station. his well known that-"moisture or liquidcondensate collects in an'air compressor tank and that serious -disadvantages"will result unless the condensate-is frequently removed: For example, excess moisture "causes =corrosionin "the-system, damage will occur if the systemis subjected "to freezingtemperatures; moisture laden air' is high- 1y objectionable in paint spraying processes, and

water-or-oi1 in an air stream employed at-a work-station for various purposes such as for cleaning-surfacesofdust; chips-and the --like is highly undesira-bla V Continual removal of Water and 'oilvapor from an-air compressor tank will keep the tankat full air capacity and-reduce the number of'times the compressor must operate tomaintain a desired pressure-.- Tliis'results in less power-andoil'vapor 'in-th'e lines. The net result is higherefliciency and longer life ofthecompressor and 'air tools.

According-to the invention,-I insertavalve in a conduit system for intermittently transmitting a gaseousfluid such" as air underpressure' and e valve is adapted tdautomatically discharge or unload liquidi-rom "the system' each time the demand for gaseous'fiuid-in the system is initiated or terminated; For example,-if-*the valve is em- :p'loye-d wi th ar-1 1 air com-pressor adapted- 190 be intermittently started andstopped,-- liquid condensate-will be discharged' each time the com pressor is started and-stopped.- The va-lve; may

13 .Claims. (o1.V1s7204-) alsobeemployed-with-an air compressor adapted to l-be'continuously' operated-and'whereiii'the pressure is periodically controlled through a-reliei .valve. V The valve may doe disposed in a service airline or. the uke :at -a poir'1t--remotei:r-omthe pressure source; such 'as a workstation; whereby upon: initiation or termination of air flow i'n the lineat the work station li'quideondensate=-will=be discharged! It ishighly-desirable that a valve-of this general type, --partieularly 5 when assoeiafte'd witli c'ompressed "air --lin es operatingair' bra-kes olosez'i or hon-venting positioii' tdavoid loss-of pressure in the airline. The instant-valve has a reciprocating slide valve V memberwhich vents moisture and-continues to a full travel position closing communication with th'event ports when movement is initiated -in either direction It' is a primary object of the invention to -provide a valveadapted to be associated with a conduit system for transmitting a gaseous fluid under pressure in'res'ponse to intermittent demands and wherein thevalve will beautomatically operated to discharge liquid condensate in the system at initiation-and cessation of-the demand.

Another object of the invention 'is to provide a valve of the above -typewhich will only stop in anon-venting or valve closed position."-

Another'objeot of the invention is-to'provide a valve of the i above type which is economical of manufacture, which -canbe -easily installedin 'a conventional conduit system -forintermittently supplying air a orthe like 'under pressure,- and whichwill operate eflic iently with a-minimum 'of attention;

Other objects of the invention and the invention itself 'willbe more clearly apparent from a consideration of the followi-ng description and drawings-wherein:

Figured is-anelevational vievalargelydiagrammaticg-of an air-compressor system havingiri-association'therewith a valve embodyingtheinvemtlon:

A Figure -2'-is an enlarged longitudinal-medial sectional view-of the valve illustrated inFigure -1, wi-tlithe slide waive member thereof in one extreme position;

Figure-3 is-a view similar 'to Figure '2 with the slide valve member inthe opposite extreme position.

Figure l-is a'medial sectional view of ;a modification of thevalve"illustrated in Figure '2 a nd Figure 5 is a fragmentary diagrammatic .vie'w showingthe valve illustrated in Figure A inserted in an'air service. line.

Referring now to the .drfawings, and particularly to Figure '1; I have indicated at .Illlaconventional 'tank'for receiving air; under pressure; the tank being supported '.'.by a suitablejframe H. Mounted on' tank I9 is an airTcomp-ressor 1 l2 drivenifroma motor I3 througha :belt .14. Air from-the compressor is, delivered under.- pressure to pipe-l6 and-then through acheck' valve A l insertedin a. pipe l 8 .to tank; 10.. ,At ll 9 .ll-have indicated a combined compressor unloaderfland pressure responsive switch. I The .fswitch'. is re sponsivetothe'pressure in pipe IE whereby when 3 demand for air from tank It ceases, the increased pressure in pipe l6 upon reaching a predetermined value will cause the switch to break the circuit to motor 3 and stop operation of the compressor. When the compressor ceases to operate, the unloader in a'well known manner will automatically reduce the pressure in pipe l5 to atmospheric pressure. Tank I is equipped with a pressure gauge 29 and air under pressure is delivered from the tank through a service pipe 2|.

The tank IB is equipped with a drain 22 which would normally be connected to a manually operable drain valve whereby liquid condensate in the tank would be periodically drained. However, as previously pointed out if the compressed air is intended to be used with paint spraying apparatus, surface cleaning apparatus, apparatus which is subjected to freezing temperature, and the like wherein air with a minimum amount of entrained water is constantly required it is impractical to have an operator available to operate the drain valve atfrequent intervals. Further, if an operator is available negligence on his part may result in considerable damage. The compressor andassociated parts so far described are conventional and are merely illustrative of the type of gaseous fluid conduit system to which a valve embodying'the invention may be applied.

To avoid the disadvantages of a manually operable drain valve I connect a pipe 23 leading from the tank drain 22 with a valve, generally indicated at 24, which embodies the invention. Valve 24 is also connected by a pipe 23 with the pipe l6 which effects communication between the compressor I2 and the tank H2.

The structure and operation of valve 24, as best illustrated in Figures 2 and 3, will now be explained. The valve comprises a tubular housing having a portion 27 provided with a cylindrical bore, a relatively short portion 28 provided with a slightly enlarged cylindrical bore, and a portion-'29 provided with a further enlarger cylindrical bore. Portion 28 in preferably of hexagonal contour externally for engagement with a wrench and portion 29 is externally threaded at the end thereof to. detachably engage a cap 3|. The external surface 32 of cap 3| is also preferably hexagonal in contour for engagement with a wrench. Portion 28 of the housing has a lateral threaded opening 33 therein forsealing connection with pipe 23. Cap 3| has an axial threaded opening 34 therein for sealing engagement with pipeiZG. It will be noted that cap 3| is formed with an annular surface 36 against which a disc 31 formed of rigid material abuts, the disc having a relatively small central opening therein as indicated at 33. Abutting disc 31 is a rubber or the like sealing ring 39.

An inner cylinder forms a slide valve member, generallyindicated at 4|. Member 4| comprises a cylindrical portion 42 which makes a sliding fit with portion 2'! of. the housing and an enlarged cylindrical portion 43 making a sliding fit with portion 29 of the housing. Portion 42 of member 4| is circumferentially grooved at three axially spaced points to receive rubber or the like sealing rings indicated at 44, 46 and 4?. Portion '43 of member 4| is. similarly grooved to receive sealing rings indicated at 48 and 43. The valve member is formed to provide an axial chamber substantially co-extensive with. portion 42 thereof anda relatively small step-shouldered axial bore extends from chamber 5| to a transverse passage 52 in the valve member enlarged portion 43. A relatively small diameter tube 53 4 has one end seated in said bore and its opposite end seated in a plug 54 which threadedly engages the small end of member 4|. Also, the valve member is grooved between sealing rings 46 and 47 to provide an annular passage 50 which communicates with chamber 5| through one or more ports 55. A plurality of radial liquid discharge ports 65 are provided in the wall of housing portion21. H.

The enlarged portion 43 of the valve member is circumferentially grooved between rings 48 and 49 to provide an annular passage 56 communicating with transverse passage 52 and resultantly with tube 53. Valve member portion 42 is drilled at axially spaced points to provide ports indicated at 51 and 5B effecting communication with chamber 5| through the valve member Wall.

The manner in which the valve illustrated in Figure 2 will function to automatically unload liquid condensate from an air compressor system of the general type illustrated in Figure 1 will now be explained. The valve 24 embodying the invention is only adapted to systems where there is an intermittent demand for air or the like under pressure as in supplying air for air brakes, in-

flating tires, paint spraying, operating pressure grease systems, pneumatic hoists and the like, as distinguished from a system which constantly demands air under pressure for long periods such as a continuous blower system. First, assume that the demand for air through service pipe 2| has ceased and consequently pressure in tank |0 reaching its maximum setting the pressure switch has broken the electrical circuit for motor l3 causing the compressor l2 to to stop operating, and the unloader has reduced the pressure in pipe |5 to atmosphere. Since pipe l6 communicates with the large end of the valve member 4| through pipe 26 the large or left end surface of the member (Figure 2) will only be subjected to atmospheric pressure. The small or right end surface of member 4| (Figure 2) is constantly subjected to atmospheric pressure sincethe end of valve housing portion 21 is always open to atmosphere. When the compressor ceases to function the check valve holds the pressure in tank ||l-at a point considerably above atmospheric pressure and this pressure is transmitted through pipe'23 to'the face 59 of member 4|, representing the difference in area between the large and small ends of the valve member. In other words, under these conditions the large and small ends of the valve member are both subjected to atmospheric pressure .but due to the higher pressure exerted on face 59 the valve member 4| will be moved to the position illustrated in Figure 2.

Now, assumethat the air is demanded in service pipe -2| whereupon the pressure switch will cause the compressor to start operating when pressure in tank I B is reduced to a predetermined Then, the large end of member 4| will be subjected to the pressure in pipe l6 whereas the opposing pressure will be atmospheric pressure on the small end of the .member plus the tan-k pressure on face 59 ofymember 4|.

Obviously thevalve member will beforced to the right '(Figure2) until the face 59 contacts the annular shoulder 6| of, the valve housing shoulder form of housingportion-H an annular passage .is formed having face 59 as one wall thereof. This passage communicates with pipe therefor. In;

. 23 and. when pressure in tank-i reaches; a predetermined maximum thus stopping the motor and compressor the pressure at the large end of 4| moves to the position illustrated inFigure 2.

Thus far I have merely explained how movement of the valve member in opposite directions is effected upon start-up or shut-down of the to the leftor vaway from housing shoulder El and the member compressor and the manner of discharging liquid condensate by movement of member4| will now be described; Although I have described the valve '24 in connection with a compressor which is intermittently operable it will be apparent that it is equally; adaptable to a compressor which is; continuously operable but which is provided with a relief valve whereby when there is no demand for air through service pipe 2 the relief valve will open to atmosphere dropping the pressure in pipe l substantially below the pressure in tank It and thereby causing the member 4| to move to the position illustrated in Figure 2 due to differential pressure on the member as previously described. As hereinbefore described when the relief valve closes due to demand for air through service pipe 2|, the member 4| will be caused to move to the right (Figure 3) due to differential pressure thereon. Relief valves of the type contemplated herein are well known and a detailed description thereof is not believed to be necessary. The manner of effecting valve member movement has been explained and if the member 4| is in the position of FigureZ, liquid condensate from tank |0 will pass through pipe 23 into the annular space defined by the inner wallof housing portion 29, the outer wall of valve member portion 42, the face 59, and the annular shoulder 5| of the housing. Liquid condensate may pass into chamber 5| through ports 57 and 58 and from the chamberIthrough port 55 into annular passage 55. As the member moves to the right passage 50 will be brought into alignment with discharge ports 50 and the liquid will be quickly discharged to atmosphere or to asuitable receiver. As previously explained, the valve member or'chamber will be. moved to the right when there is a demand for increased air pressure intank hand when face 59 contacts housing shoulder 5| as, illustrated in Figure 3, annular passage 50 will have moved to. the right beyond housing discharge ports 50 andthe discharge ports will be covered by the member portion intermediate the sealing rings 44 and 46. At this time portsfi'i' and 58' of the valve mem ber. are in communication with tank drainpipe 23 and liquid co derlsate will be forced into charn-l ber 5| under tank pressure: Whenthedemand for air pressure in tank l5 ceases, thevalve member will start moving to the leftand when passage 55 is again aligned with discharge ports 60 afurther discharge' of liquid condensate will occur. l'Ihus, condensate is jidischarged bothupon initiation of demand for air in pi zl andupon termination of s uch demand wh'ere by an air supply system subject to intermittent demands is automatically maintained substantially free of moisture or liquid condensate;

[I contemplate that additional" ports 'may be drilled through th wallof portion of member, 4| between ports .57 and 53.0r the wall ofportion 42 extendi g} from ports I51 58be omitted and a. cylindrical screen. substituted t n a m ri elp gee employed I preferably formportions 42 and 43 of member 4| as separate parts and inter-connect .these portions by threading tube 53 into portion trapped between these rings. The provision of two sealingrings 48 and'49 for enlarged portion 43 of valve member 4| and an intermediate passage 56 communicating with atmosphere is important.- As previously pointedout, the face 59 of valve member 4| is continuously subjected to tankpressure or high pressure whereas the pressure at the large or left hand end of the valve whichis telescoped the lower endof a cylinder member will be intermittently reduced to atmospheric pressure. Under these conditions liquid condensate and/oroil vaporfrom tank l0 entering the housing of valve 24 through pipe 23 may be forced past sealing ring 48 and if only one sealing ringis used the 1iquid would be forced into pipe 26. In fact, I found by experiment that if only one sealing ring is employed after a period of several months pipe 25 may become entirely filled with liquid and prevent proper functioning of the compressor-unloader unit. With the arrangement disclosed anyliquid forced by sealing ring 48 is trapped by the second sealing ring 49 and drained through passages 55, 56 and tube 53. To prevent sudden movement of the valve member 4| to the left. or shock contact of the member with the housing cap I provide the relatively small or restricted opening 38 in disc 31 which in a well known manner retards member movement. It will be notedthat the valve housing, cap 3|, and the valve chambermember are adaptable to being primarily formed by automatic screw machine operations. I preferably use hexagonal bar stock for the cap and housing.

The rubber sealing or 0 rings are inserted in the grooves provided therefor in the external 'walls of the member and after member 4| is disposed in the housing, the valve is assembled by threading cap 3| to the housing. It will be apparent that the valve described is economical of manufacture and can be adapted to a conventional air compressor system adapted to intermittently supply air under pressure, merely by substituting the valve 24 for a conventional manually operated drain valve through connection of 'valve'opening 33 with the tank drain pipe and extending a pipe 26 from valve opening 34 to a point in the air line between the compressorunloader and compressor. Y

Referring now to Figure 4, I have shown a modification of the valve illustrated in Figures 2 and 3; The valve generally'indicated at 63 has a housing formed by an upper part 54 of inverted cupform, a lowerjcup form part 66, and a tube 61 depending from part 66. Parts 64 and'fiB are formed with outwardly extending radial flanges and the flange of an element 53 gripped there'- between, Sealing rings 69 are disposed between the flanges and the flanges are secured together in any suitable manner as by screws 1|. Elernent'iiiiv has an upstanding neck portion over The lower end of 'the cylinder is sealed with element 58 as by a sealing ring 13 and the upper end 'is sealed withhousing part 64 as by a gask- 7 Tube 8'1 sealin l connected to lower housing part B S-iii any suitable manner as by pro; vidingr' an outwardly radial flange at th tune upper end and clampinga-sealing ring: 16 between the tube flange and the base or part 661 by a snap ring 11 seating" in agroo've the tube; EX-

a c lindrical screen 18; the screen preferably being ion-nod with a radial-flange 19 at its lease force terin the screen iii-part 66. A A piston 81 provided with sealing: ringsei which may be rubher ringsos shown orsplit metal rings is reciprocable in: cylinder 12 and has a rod 83 secures therein, A bleed hole 95 efiects' communication betweenchamber 93, and the top zone of cylinder 12; I

Therocl at-itsiower end is secured to a tubular valve member an in any suitable manner'as by termn s tepereo plug-a6 the rod one and threading the-same intothevalveinemoer therevide discharge ports asi'i-idicated at- 92.

effect, the flangeor element 6t divides the interior of thevalive housing into ari upper chamber 93 and a lower chamber E345 and: a bleed hole 96 provides continuous communication between the chambers Anplurality'of por tsBI are formed in" cylinder 12' in a positionto be disposed above piston 31in its-lowermost position and to be beneath the piston in itsuppermos'tposition. Lower housing part 68 is provided with a threaded boss 98' for connection with a line" such as 2 t leading from an: air compressor tank and the u per valve part 64- is provided with a threaded boss 99- for connection with aline Hill leading to an air tool or other apparatus intermittently demanding air under pressure. For ease in removal I contemplate that a cup form screen can be substituted for screen 18 and disposed with its axis horizontaland its open end disposed in bass 981- The screen open end would have a radial outwardly extending flange: seating against annular shoulder on the boss. V 7

T hemanner in which the valve illustrated in Figures 4 and 5 operates will now be described. Since lower chamber 94 is connected totank- [0 byline if it is continuously subjected to tank or relatively high pressure The lower face oi piston 81 and the valve member 84 are bothsubjected to the air pressure ii -chamber 4 and tend to move the rod 83* in opposite directions but the 'net effective area is such as to tend to move the rod' in an upward direction. When the demand for air at the tool" or the like associated with line lfl'llis' cut off the air pressure" in chambers 93 and 9'4'wil1 quickly equalize since tlie'cliambers' cornmunicate through bleed hole 961' Under these conditions'th'e upper'faee of piston 8 [is subjected to the samepressureas the'underf'ace but theef festive area is greater so that the piston is forced downwardly to the position illustrated in Figure 4*. When air'is'demandedin'line fmYtheairpre'ssure in chamb-er93 quickly drops to a point where the piston is forced upwardly so that its lower face is above c lind'e'r ports 91' permitting'a free flow ofair between lines 21 andllifi. Since the area. of bleed hole 96 'is' 'relativeiy' small it can'- not supply air at a rate to prevent a quickdrol'i iii pressure in charmer-9'3 when air is demanded injiiie Hit.

ii-tithe base OfI O'WI valve part es; Liquid c5011- densate will collect the hase oi' art 66 and the'w'ell of valve member 84;- Liquid in the valve member will be discharged to atmosphere or a receptacle when the i i'imbr dp liifls; 9] are aligned with the" tube discharge parts 92 or durfiii time the" annular Zfi btwe'ii rings- 88 and 8 9 is aii g ent With-p" 92; Liquid in the valve mom-o'er" will bis-discharged both on the up and down strokes of the valve memberor each time air now starts and stops in line I00;

The manner in which; valve (is is adapted to lEl'ifibil-l a-fiialiy remove liquid condensate fioifi air service'lirie has been described. e valve can alsoremove condensate ai r'eempressor 'iiiiiiksuch: as T merely by fil'icfii iig' dram iiiii 2 3 (Figure 1)" with the valve housinglOWi part througl i'boss 98 connecting the all service Iine'su'ch as 21 With-the valve h using u per part through; a pipe etending from boss 99 to line 21 adi-aeerit' the tan-k.- With this hook-up chamber 9"4 is always subjected to tank pressure and chamber 93-i'salternate1y' subi'ectedto tanlopressure and a rel tively lower "ssure air flows in line 2L Thus previously described the valve member will be; reciprooatecl as air flow is demanded and cut oii-inthe service line to discharge condensate frointanlr- Hi. i

It ill be noted that in both the valves illustrated in Figures 2 time the valve memlieroiits ofi communication with the-discharge to atmosphere in-ei-ther of its extreme positions. Also, it will be noted that when inivem'entof the valve member is initiated in either direction it continues to its other extreme position.- It is particularly im ortant in airbrak e systems that air pressure isnot reduced throu h continuous" ventin or a moisture unlcader valve in the system and the instant valve prevents continuous venting of air;- It will be noted: that bot-h the valves illustratedhave a ylinder in which apiston'is reci-procable',- a mother portion in whi h a s1ide"va1've member fixed-to the piston is re'oiprocable', the slide valve nieniber has a chamber or well for receiving oondensate'aiid adapted tobe continuously subjected to relatively high pressure, and that the wellis adapted to temporarily communicate with atmosphere during reverse movements ofthe valve irreinher. Iw'is'h it to be understood that-i do not desire to-be' limited to the exact details of construction shown and described for otvicus modification will gocnr to persons skilled in the art; What I" ola'ir'n is as follows: I Ali-quid" unloading valve adapted to beinsjerted in o conduit system for supplying aseous fluid under :p'r'e'ssure response to intermittent demanusthe valve"- being adapted to discharge liquiuxentrainerr the gaseous fluid n'pon initiat tion'and cessation 'ofsuch demands; said valve comprising a tubular housingiiavifig an opening therein adapted to communicate witl'i'gaseou's fluid under" substantiallyoonstant high ressure and a second oper llifig" adapted" to communicate with ase us-- fluid nnd'er variable pressure; a, cylindrical slidey alvemember the housing havingja: piston integral therewith; wit-ii one face of the? istoncommunicating with the" constant pressure openiflgjandtheidt e'rfac'e communicat iilgwitl-r thevariable pressure opening, theval've ,9, member being adapted to move'in one directio when the variable pressure changes in response to cessation of demand for gaseous fluid'and to move in-the opposite direction when thevariable pressure; changes in responseto demand for.

gaseous'fluid, the slide valve member 'having a longitudinally extending chamber therein, means effecting continuous: communication between said chamber and the constant pressure opening whereby liquid entrained in the gaseous'fiuid may bedirec'ted to the cliamberftheivalve housing having liquid discharge means therethrough, the

valve member having liquid discharge means communicating with the chambertherein, and

both said liquid'discharge means beingadapted; to be aligned whenthe valve membermoves-in' either direction relative to the valvehousing whereby liquid will be discharged from the valve upon initiation and cessation of deman d for gaseous fiuid. I I I A I 2. Aliquid unloading valve fora system adapted to deliver air under substantially constant having 'a second opening therein adapted to be connectedto a conduit for air subject to variable pressure in response to'initiation and cessation of demands for air in the systeni the opposite face of the piston being in' communication with the variable'pressure opening whereby differential pressure on the piston will cause the valve member to move in opposite directions, the valve member having an elongate chamber therein,

means effecting continuous communication; between said chamber a'ndthe constantpressure opening whereb'y liquid maybedelivered to said chamber, the housing having transversely aligned liquid discharge openings therein, and the valve member having liquid dischargeports from the chamber whereby whenthe discharge ports are aligned with the discharge openings upon movement of the valve member in either direction liquid will be discharged from the chamber through said housing. 1

3. A liquid unloading valve adapted to be associated with an air compressor system of the type comprising a tank, a liquid drain for the tank, a compressor, and an air supply pipe leading from the compressor to the tank adapted to have the pressure therein reduced substantially below tank pressure upon cessation of demand for air from the tank, said valve comprising a tubular housing having an enlarged-cylindrical bore extending to a reduced cylindricalbore, a cylindrcal slide valve member in the housing having a tubular portion slidable in the housing reduced bore and an enlarged piston portion slidable in the housing enlarged bore, the housing having a first opening therein adapted to effect communication between the tank drain and one face of the piston portion, the housing having a second opening therein adapted to eifect communication between the tank air supply pipe and the opposite face of the piston portion whereby the valve member will be moved in opposite directions in response to diiferential pressure between the tank and said air supply pipe, the valve member tubular portion wall having an entry opening efiecting constant communication with the housing first opening whereby liquid from the tank 7 may be delivered to the interiorof the tubular portion, the said tubular portion'wall having 'a' liquid discharge-opening axially spaced from'the" entry opening, and the housing having'liquid discharge ports'whereby liquid will be discharged from the valve when the valve'lmeinb'er discharge opening is aligned'with said discharge ports upon movement of the valve member in either direction. I o

4. A liquid unloading valve for use. With'SYS- tems supplying gaseousfluid under pressure, said.

valve comprising a tubular housing open to atmosphere at one end and'closed at its opposite. end, the housing'being formed to provide an.

enlarged cylindrical bore extending from its closed end'and a reduced co-axial cylindricalbore' extending to its open end, the housing closed end being adapted to communicate with .a source of gaseous fluid under variable pressure, the housing having an opening in the side wall thereof at the juncture of the enlarged'and reduced bores therein adapted to communicate witha source of gaseousfluid under substantially constant pressure, the housing having a plurality of radial liquid discharge ports at a transverse plane adjacent the opemendthereof, a cylindrical slide valve member in the housing having a tubular portion slidable in the housing reduced bore 'and' a piston slidable in the housing enlarge'd bore,- the tubular portion providing an elongate'closed chamber in the valve member, the valve me'mber having openings in the chamber wall eifect" ing continuous communication between "the chamber and the housing side wall opening, and the chamber walls having liquid discharge openings therein adapted to be aligned with the'hous-' ing discharge ports during travel of the valve member. 3

5. The liquid unloading valve as described in" claim4 'andwherein' sealing rings are mounted in the valve member ateach side of the chamber liquid discharge openings, and the tubular portion of the valve member is formed 'with"an 2 external groove forming an annular pas'sage communicating with said discharge openings;

6. The liquid unloading valve as described in claim 4 and wherein" the valve member piston" has axially spaced sealing rings mounted there-'- in, the-piston is grooved to, form an annular passage between saidrings, a tube extends from the piston throughthe valve member chamber in) atmosphere, and the piston is formed with a'trans-' P e; a

verse passage connecting said annular and tube.

'7. The liquid unloading valve as d'escribed in claim 4 and wherein the housing closed endcom prises a detachable cap 'adaptedto engage a conduit, a sealing ring, and a disc having arestricted orifice whereby valve member movement towards the closed end of the housing will be retarded.

8. A liquid unloading'valve comprising a cylinder, a tubular portion of reduced cross-sectional area relative to the cylinder and axially aligned therewith, a piston reciprocable in the cylinder, a slide valve member reciprocable in the tubular portion and fixed to the piston, the valve member having a well therein adapted to continuously communicate with a gaseous fluid under relatively high pressure and to receive liquid condensate, one face of the piston having less effective area than the opposite face and said one face being adapted to be continuously subjected to said high pressure, the said opposite subjected to relatively high and 'low pressure whereby the pistonand valve member will be reciprocated due to differential force on the piston, and meanseffecting temporary communication between the valve member well and atmosphere during movement of the valve member in either direction whereby condensate may be discharged. v

9. A liquid condensate unloading valve for air compressor systems adapted to be inserted in any system wherein a first connection can be made witha source of substantially constant relatively high pressure and a second connection can be made with a line intermittently having a pressure generally corresponding to said high pressure and a relatively lower pressure, said valve comprising a housing including a cylinder, a tubular portion axially aligned with the cylinder and of reduced cross-sectional area relative thereto, a, piston reciprocable in the cylinder, a hollow slide valve member in the tubular position operatively connected to the piston and adapted to receive liquid condensate from the housing, one face of the piston having. a greater effective area than its opposite face whereby substantially the same air pressure on both faces will effect movement of the piston and valve member in one direction and a substantially reduced pressure on the opposite fac will efiect movement in the op osite direction, means for making the said first connection withthe housing at a point to exert its substantially constant pressure on the said opposite piston face, means to make the said second connec-' tion with the housing at a point to exert its variable pressure on the said one piston face, the slide valve member having discharge openings at a transverse zone therein, and the tubular portion having discharge ports at a transverse zonev whereby liquid condensate'will be discharged from the valve when communication is efiected between the discharge openings and ports during travel of the valve member'in either direction.

10. The liquid unloading valve as described in claim 9 and wherein sealing rings are disposed at axially spaced points between the slide valve member and tubular portion to define an annular Zone therebetween for receiving condensate to be discharged.

11. The liquid unloading valve as described in claim 9 and wherein screen means are disposed in the housing adapted to prevent entrained for'-, eign matter in air flowing from the high pressure source from entering the interior of the slide valve member.

12. A liquid unloading valve for compressed air systems and the like comprising a housing hav ingan upper and lower chamber therein, means for connecting the upper chamber with a line intermittently demanding air under pressure, means for connecting the lower chamber with a source of air under substantially constant high pressure,-

a ported cylinder encircled by the upper chamber, a reciprocable piston in thecylinder adapted to move from a position effecting communication between the chambers through the cylinder ports to a position cutting off communication, a bleed port between the chambers, the lower face of the piston subjected to pressure in the lower chamher having less effective area than its upper face whereby when air demand from the upper chamber ceases the chamber pressures quickly equalize forcing the piston downwardly to cut off communication between the chambers and when demand initiates the piston moves upwardly due to lower pressure in the upper chamber to effect communication between the chambers, a hollow slide valve member operable by the piston adapted to receive liquid condensate from the lower chamber, and means for discharging said condensate to atmosphere upon reverse movements of the slidevalve member.

13.- A liquid unloading valve adapted to be inserted in an air'supply conduit subjected to intermittent demands, said valve comprising a tubular housing having an air entry port, a cylinder in the housing, a piston in the cylinder, the'cylinder having an opening in continuous communication with the air entry port, the cylinder having an air discharge port adapted to connect with a conduit for intermittently supplying air, the piston being movable in opposite directions in response to initiation and cessation of air demand at the discharge port whereby upon air demand the piston will move to a position effecting communication between the entry and discharge ports and upon cessation of-demand the piston will move to a position cutting offcommunication between said ports, the housing having a depending reduced tubular-portion co-axial with the cylinder, a slide valve member in the housing reduced portion rigidly connected to the piston and adapted to receive liquid condensate from the housing, the valve member having liquid dis-' charge openings at a transverse plane,jand the housing reduced portion having ports adapted to discharge liquid when the valve member openings are aligned therewith upon movement of the valve member in opposite directions.

. RALPH A. BARRETT.

REFERENCES CITED The following references are of record in the nicer this patent:

UNITED STATES PATENTS Number Name Date 2,007,358 Anger July 9, 1935 2,059,808 Robart et a1. Nov. 3, 1936 18,4 White et a1. 0;--- Apr. 1, 194 

